US4883634A - Process for manufacturing a high modulus poly-p-phenylene terephthalamide fiber - Google Patents

Process for manufacturing a high modulus poly-p-phenylene terephthalamide fiber Download PDF

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US4883634A
US4883634A US07/041,589 US4158987A US4883634A US 4883634 A US4883634 A US 4883634A US 4158987 A US4158987 A US 4158987A US 4883634 A US4883634 A US 4883634A
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fiber
yarn
fibers
poly
polymer
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Terry S. Chern
Stephan C. De La Veaux
Jacob Lahijani
James E. Van Trump
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EIDP Inc
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EI Du Pont de Nemours and Co
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Priority to US07/041,589 priority Critical patent/US4883634A/en
Priority to IN413/CAL/87A priority patent/IN171087B/en
Priority to CA000537985A priority patent/CA1290117C/en
Priority to BR8702726A priority patent/BR8702726A/pt
Priority to AU73483/87A priority patent/AU607420B2/en
Priority to KR1019870005386A priority patent/KR940002380B1/ko
Priority to EP87304765A priority patent/EP0247889B1/de
Priority to FI872403A priority patent/FI872403A/fi
Priority to IL82709A priority patent/IL82709A/xx
Priority to DK275587A priority patent/DK275587A/da
Priority to DE8787304765T priority patent/DE3772628D1/de
Priority to PT84981A priority patent/PT84981B/pt
Priority to ES87304765T priority patent/ES2025162B3/es
Priority to NO872270A priority patent/NO169138C/no
Priority to AT87304765T priority patent/ATE66971T1/de
Priority to MX006705A priority patent/MX166780B/es
Priority to JP62133544A priority patent/JPH0778289B2/ja
Assigned to E. I. DU PONT DE NEMOURS AND COMPANY, WILMINGTON, DE. A CORP. OF DE. reassignment E. I. DU PONT DE NEMOURS AND COMPANY, WILMINGTON, DE. A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CHERN, TERRY S., DE LA VEAUX, STEPHAN C., LAHIJANI, JACOB, VAN TRUMP, JAMES E.
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    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
    • D01F6/62—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyesters
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F6/00—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof
    • D01F6/58—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products
    • D01F6/60—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides
    • D01F6/605—Monocomponent artificial filaments or the like of synthetic polymers; Manufacture thereof from homopolycondensation products from polyamides from aromatic polyamides
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D10/00—Physical treatment of artificial filaments or the like during manufacture, i.e. during a continuous production process before the filaments have been collected
    • D01D10/02—Heat treatment

Definitions

  • Poly-p-phenylene terephthalamide fibers long known for their light weight, high strength, and high modulus, have found wide acceptance in a great number of applications requiring their unique combination of properties. The wide acceptance has, however, given rise to a demand and need for fibers having still higher strength and modulus for use in still more demanding applications. Fibers having decreased solubility and chemical reactivity and increased overall crystallinity and resistance to moisture regain have been sought and are in demand.
  • U.S. Pat. No. 3,869,430 issued Mar. 4, 1975 on the application of H. Blades, discloses fibers of poly-p-phenylene terephthalamide and processes for making the polymer and the fibers. That patent is particularly concerned with a process for heat treating such fibers after the fibers have been dried. That patent discloses, generally, that fibers could be heat treated whether wet or dry; but, in the examples, teaches heat treatment only of dried fibers and, elsewhere in the specification, cautions against heat treating fibers at excessive heat for excessive time with the warning that decreased tenacity and decreased polymer inherent viscosity will result.
  • Japanese Patent Publications Nos. 55-11763 and 55-11764 published Mar. 27, 1980 disclose fibers of poly-p-phenylene terephthalamide having high modulus and high tenacity but with polymer exhibiting only moderate inherent viscosity.
  • the processes of those publications are particularly concerned with a fiber-drawing step performed after coagulating the spun polymer and before drying the fibers.
  • the fibers are actually stretched to 20 to 80 or 90% of the maximum stretch attainable before break. After the stretching, the fibers are dried at various times and at temperatures above about 300 degrees and as high as 600 degrees for three seconds.
  • the inherent viscosity of the polymer of fibers so-made is always disclosed to be less than the inherent viscosity of the starting polymer and there is no suggestion that the inherent viscosity might be increased by any heat treatment.
  • a process is provided by this invention for manufacturing a poly-p-phenylene terephthalamide fiber having high modulus and high tenacity wherein a wet, water-swollen, fiber is exposed to a heated atmosphere, and the fiber, during exposure, is subjected to a tension.
  • the swollen fibers preferably, have about 20 to 100 percent water, based on dried fiber material, and the atmosphere is usually heated at 500 to 660 degrees with exposure of the fiber for 0.25 to 12 seconds.
  • the tension on the fiers is about 1.5 to 4 grams per denier (gpd).
  • an entrainment jet is used for application of hot gas to dry and treat the swollen fibers in an efficient and effective manner.
  • the process is very fast and, as a result, the product of the jet embodiment of the process is a fiber having a Crystallinity Index of greater than 75%.
  • the swollen fiber should be exposed to a heated atmosphere at 500 to 660 centigrade degrees for about 0.25 to 3 seconds, and most preferably about 0.5 to 2 seconds. In the most preferable range, there is some allowance made for different sizes of yarns--the range is most preferably 0.5 to 1 second for 400 denier yarns and 0.5 to 2 seconds for 1200 denier yarns.
  • an oven is used for application of radiant heat to cause slower drying of the swollen fibers; and, as a result, the product of the oven embodiment is a fiber having an inherent viscosity of more than about 6.5.
  • the swollen fiber should be exposed to a heated atmosphere at 500 to 660 degrees for about 3 to 12 seconds, and most preferably at 550 to 660 degrees for about 5 to 12 seconds, with less time required for low denier yarn at a given temperature.
  • radiant heating of the oven embodiment means that at least 75 percent of the heat energy absorbed by the water-swollen yarn is radiant heat energy.
  • the present invention is based on a treatment of poly-p-phenylene terephthalamide fibers which, quite unexpectedly, gives rise to fibers of high modulus and Crystallinity Index while permitting controlled increase of the ultimate inherent viscosity.
  • the invention permits manufacture of high modulus fibers of poly-p-phenylene terephthalamide, having inherent viscosity of greater than 6.5 and Crystallinity Index of greater than about 75%.
  • poly-p-phenylene terephthalamide is meant the homopolymer resulting from mole-for-mole polymerization of p-phenylene diamine and terephthaloyl chloride and, also, copolymers resulting from incorporation of small amounts of other aromatic diamine with the p-phenylene diamine and of small amounts of other aromatic diacid chloride with the terephthaloyl chloride.
  • aromatic diamines examples include m-phenylene diamine, 4,4'-diphenyldiamine, 3,3'-diphenyldiamine, 3,4'-diphenyldiamine, 4,4'oxydiphenyldiamine, 3,3'-oxydiphenyldiamine, 3,4'-oxydiphenyldiamine, 4,4'-sulfonyldiphenyldiamine, 3,3'-sulfonyldiphenyldiamine, 3,4'-sulfonyldiphenyldiamine, and the like.
  • aromatic diacid chlorides examples include 2,6-naphthalenedicarboxylic acid chloride, isophthaloyl chloride, 4,4'-oxydibenzoyl chloride, 3,3'-oxydibenzoyl chloride, 3,4'-oxydibenzoyl chloride, 4,4'-sulfonyldibenzoyl chloride, 3,3'-sulfonyldibenzoyl chloride, 3,4'-sulfonyldibenzoyl chloride, 4,4'-dibenzoyl chloride, 3,3'-dibenzoyl chloride, 3,4'-dibenzoyl chloride, and the like.
  • aromatic diamines and other aromatic diacid chlorides can be used in amounts up to as much as about 10 mole percent of the p-phenylene diamine or the terephthaloyl chloride, or perhaps slightly higher, provided only the other diamines and diacid chlorides have no reactive groups which interfere with the polymerization reaction.
  • Poly-p-phenylene terephthalamide fibers which include such small amounts of other diacids or diamines and which are heat treated by this invention, may exhibit physical properties slightly different from those which would have been obtained had no other diacids or diamines been present.
  • the polymer can be conveniently made by any of the well known polymerization processes such as those taught in U.S. Pat. No. 3,063,966 and U.S. Pat. No. 3,869,429.
  • One process for making the polymer includes dissolving one mole of p-phenylene diamine in a solvent system comprising about one mole of calcium chloride and about 2.5 liters of N-methyl-2-pyrrolidone and then adding one mole of terephthaloyl chloride with agitation and cooling.
  • the addition of the diacid chloride is usually accomplished in two steps;--the first addition step being about 25-35 weight percent of the total with the second addition step occurring after the system has been stirred for about 15 minutes.
  • Cooling is applied to the system after the second addition step to maintain the temperature below about 60° C. Under forces of continued agitation, the polymer gels and then crumbles; and, after a few hours or more, the resulting crumb-like polymer is ground and washed several times in water and dried in an oven at about 100°-150° C.
  • Molecular weight of the polymer is dependent upon a multitude of conditions. For example, to obtain polymer of high molecular weight, reactants and solvent should be free from impurity and the water content of the total reaction system should be as low as possible --no more, and preferably less, than 0.03 weight percent. Care should be exercised to assure the use of equimolar amounts of the diamine and the diacid chloride because only a slight imbalance in the reactant materials will result in a polymer of low molecular weight. While it may be preferred that inorganic salts be added to the solvent to assist in maintaining a solution of the polymer as it is formed, quaternary ammonium salts have, also, been found to be effective in maintaining the polymer solution.
  • Examples of useful quaternary ammonium salts include: methyl-tri-n-butyl ammonium chloride, methyl-tri-n-propyl ammonium chloride, tetra-n-propyl ammonium chloride, tetra-nbutyl ammonium chloride, and the like.
  • Fibers are made in accordance with the present invention by extruding a dope of the polymer under certain conditions.
  • the dope can be prepared by dissolving an adequate amount of the polymer in an appropriate solvent.
  • Sulfuric acid, chlorosulfuric acid, fluorosulfuric acid and mixtures of these acids can be identified as appropriate solvents.
  • Sulfuric acid is much the preferred solvent and must be used at a concentration of 98% or greater to avoid undue degradation of the polymer.
  • the polymer should be dissolved in he dope in the amount of at least 30, preferably more than 40, grams of polymer per 100 milliliters of solvent.
  • the densities of the acid solvents are as follows: H 2 SO 4 , 1.83 g/ml; HSO 3 Cl, 1.79 g/ml; and HSO 3 F, 1.74 g/ml.
  • the polymer Before dissolving the polymer to make the spinning dope, the polymer should be carefully dried to, preferably, less than one weight percent water; and the polymer and the solvent should be combined under dry conditions. Dopes should be mixed and held in the spinning process at as low a temperature as is practical to keep them liquid in order to reduce degradation of the polymer. Exposure of the dopes to temperatures of greater than 90° C. should be minimized.
  • the dope once prepared, can be used immediately or stored for future use. If stored, the dope is preferably frozen and stored in solid form in an inert atmosphere such as under a dry nitrogen blanket. If the dope is to be used immediately, it can conveniently be made continuously and fed directly to spinnerets. Continuous preparation and immediate use minimizes degradation of the polymer in the spinning process.
  • the dopes are, typically, solid at room temperature and behave, in spinning, like polymer melts.
  • a dope of 45 grams of the polymer with an inherent viscosity of about 5.4 in 100 milliliters of 100% sulfuric acid may exhibit a bulk viscosity of about 900 poises at 105° C. and about 1000 poises at 80° C., measured at a shear rate of 20 sec -1 ,and would solidify an opaque solid at about 70° C.
  • the bulk viscosity of dopes made with a particular polymer increases with molecular weight of the polymer for given temperatures and concentrations.
  • Dopes can generally be extruded at any temperature where they are sufficiently fluid. Since the degree of degradation is dependent upon time and temperature, temperatures below about 120° C. are usually used and temperatures below about 90° C. are preferable. If higher temperatures are required or desired for any reason, processing equipment should be designed so that the dope is exposed to the higher temperatures for a minimum time.
  • Dopes used to make the fibers of this invention are optically anisotropic, that is microscopic regions of the dope are birefringent and a bulk sample of the dope depolarizes plane-polarized light because the light transmission properties of the microscopic regions of the dope vary with direction. It is believed to be important that the dopes used in this invention must be anisotropic, at least in part.
  • Fibers of the present invention can be made using the conditions specifically set out in U.S. Pat. No. 3,869,429.
  • Dopes are extruded through spinnerets with orifices ranging from about 0.025 to 0.25 mm in diameter, or perhaps slightly larger or smaller. The number, size, shape, and configuration of the orifices are not critical.
  • the extruded dope is conducted into a coagulation bath through a noncoagulating fluid layer. While in the fluid layer, the extruded dope is stretched from as little as 1 to as much as 15 times its initial length (spin stretch factor).
  • the fluid layer is generally air but can be any other inert gas or even liquid which is a noncoagulant for the dope.
  • the noncoagulating fluid layer is generally from 0.1 to 10 centimeters in thickness.
  • the coagulation bath is aqueous and ranges from pure water, or brine, to as much as 70% sulfuric acid. Bath temperatures can range from below freezing to about 28° C. or, perhaps, slightly higher. It is preferred that the temperature of the coagulation bath be kept below about 10° C., and more preferably, below 5° C., to obtain fibers with the highest initial strength.
  • the dope After the extruded dope has been conducted through the coagulation bath, the dope has coagulated into a water-swollen fiber and is ready for drying and heat treatment.
  • the fiber includes about 20 to 100% percent aqueous coagulation medium, based on dry fiber material, and, for the purposes of this invention, must be thoroughly washed to remove the proper amount of salt and acid from the interior of the swollen fiber. It is now understood that fiber-washing solutions can be pure water or they can be slightly alkaline.
  • Washing solutions should be such that the liquid in the interior of the swollen fiber should have an acidity less than 60 and preferably less than 10 and a basicity less than 10 and preferably less than 2 depending upon the conditions of the heat treatment and the desired final inherent viscosity of the fiber product.
  • acidity of up to about 60 meq of acid per kg of yarn is acceptable. Within that acidity limit, process operability and product properties are acceptable.
  • the upper limit of 60 acidity approximately corresponds to what is believed to be the sum of acid groups attached to poly-p-phenylene terephthalamide polymer.
  • the acid groups are made up of carboxylic acid groups and sulfonic acid groups.
  • a base such as sodium hydroxide
  • the acid groups react with and neutralize basic groups which are present in the fiber as a result of such washing processes. Above about 60 meq of acid per kg of yarn, product quality and processability deteriorate sharply.
  • poly-p-phenylene terephthalamide fibers containing this level of base showed no change in inherent viscosity.
  • inherent viscosity was sharply reduced.
  • about 400 milliequivalents of sodium hydroxide in poly-p-phenylene terephthalamide fibers even at oven temperature as low as 410° C. for 5 sec, caused a dramatic drop in fiber properties to 3.0 inherent viscosity, 3.7 gpd tenacity and 450 gpd modulus.
  • Increased inherent viscosity indicates an increase in molecular weight of the polymer which constitutes the fiber product. Fibers of polymer having moderately increased molecular weight exhibit decreased solubility and, also, exhibit increased resistance to deterioration due to moisture and chemical exposure. Fibers of polymer having greatly increased molecular weight, such as indicated by an inherent viscosity of 20, or greater, exhibit complete insolubility.
  • the washing medium for practice of this invention should be neutral or slightly basic.
  • FIG. 1 depicts a jet which is effective for practice of this invention.
  • the jet includes a fiber introduction back part 1, a fluid introduction body part 2, and a heat treating barrel extender 3. Fiber 4 is introduced into back part 1 at fiber feed orifice 5, is conducted through that part to heat chamber 6, and from there through barrel extender 3. Heated fluid is introduced into heat chamber 6 by means of conduits 7 which may be present around heat chamber 6 in any number of one or more and, if more than one, substantially equally spaced.
  • the heated fluid and the fiber to be heat treated are conducted through barrel extender 3 in the same direction, at the same or different speeds. Some of the heated fluid also exits through the fiber feed orifice 5 in the back part 1 so as to avoid entrainment of cool, outside, gases.
  • the speed of the heated fluid is carefully selected to provide high heat transfer from the fluid through the jet device. For the purpose of this invention, it has been concluded that a flow designated by a Reynolds Number of greater than about 10,000 is preferred.
  • jet as a means for heating fibers permits heating convectively at rates of approximately ten times the rate which is obtained using a radiant oven.
  • the Reynolds Number or the degree of turbulence of gas in the jet has been taken to be substantially independent of the yarn or fiber moving through the jet.
  • the rate of movement of the yarn or fiber through the jet is important only to provide the desired or required heating time.
  • the turbulent flow of the heated gas can be countercurrent to the movement of the yarn or fiber being heat treated.
  • FIG. 2 depicts an oven which is effective for practice of this invention.
  • the oven includes a tube 10 with fiber introduction end 11 and fiber exit end 12.
  • Tube 10 is contained in insulating jacket 13 and there is provision for introducing heated fluid into tube 10 by means of conduits 14 which may be present around tube 10 in any number of one or more and, if more than one, substantially equally spaced.
  • Fiber 15 to be heat treated is conducted through the oven at a speed adequate to permit drying the fiber and exposing the dried fiber to the proper heat energy.
  • the heating fluid is supplied at a rate which is adequate to maintain a desired temperature in the oven and carry evaporated swelling medium away.
  • the jet embodiment utilizes turbulent heated fluid flow with a resultant, very thin boundary layer and very high, substantially convective, heat transfer
  • the oven embodiment utilizes relatively slow moving, laminar, heated fluid flow with a resultant relatively thick boundary layer and low, substantially radiant, heat transfer.
  • the description of this invention is directed toward the use of fibers which have been newly-spun and never dried to less than 20 percent moisture prior to operation of the heat treating process. It is believed that previously-dried fibers cannot successfully be heat treated by this process because the heat treatment is effective when performed on the polymer molecules at the time that they are being dried and ordered into a compact fiber structure.
  • test procedures represent descriptions of methods used to evaluate the fibers prepared, in the Examples, as exemplifying the instant invention.
  • c is the concentration (0.5 gram of polymer in 100 ml of solvent) of the polymer solution and ⁇ rel (relative viscosity) is the ratio between the flow times of the polymer solution and the solvent as measured at 30° C. in a capillary viscometer.
  • ⁇ rel relative viscosity
  • the inherent viscosity values reported and specified herein are determined using concentrated sulfuric acid (96% H 2 SO 4 ). Inherent viscosities reported as 20 dl/g or greater are indications that the polymer being tested is insoluble. Fibers of this invention can be insoluble.
  • twist multiplier (TM) of a yarn is defined as: ##EQU3##
  • the yarns tested in Examples 1-16 and 25-33 were conditioned at 25° C., 55% relative humidity for a minimum of 14 hours and the tensile tests were conducted at those conditions.
  • the yarns tested in Examples 17-24 were conditioned at 21° C., 65% relative humidity for 48 hours and the tensile tests were conducted at those conditions.
  • Tenacity (breaking tenacity), elongation (breaking elongation), and modulus are determined by breaking test yarns on an Instron tester (Instron Engineering Corp., Canton, Mass.).
  • Tenacity and elongation are determined in accordance with ASTM D2101-1985 using sample yarn lengths of 25.4 cm and a rate of 50% strain/min.
  • the modulus for a yarn from Examples 1-16 and 25-33 was calculated from the slope of the secant at 0 and 1% strains on the stress-strain curve and is equal to the stress in grams at 1% strain (absolute) times 100, divided by the test yarn denier.
  • the modulus for a yarn from Examples 17-24 was calculated from the slope of a line running between the points where the stress-strain curve intersects the lines, parallel to the strain axis, which represent 22 and 27% of full load to break (Full scale to break for 400 denier yarns was 20 pounds and for 1200 denier yarns was 100 pounds). Results from tests of the two methods for determining modulus are believed to be substantially equivalent. For purposes of determining yarn moduli in claim conformance, the method of Examples 1-16 and 25-33 will be used.
  • the denier of a yarn is determined by weighing a known length of the yarn. Denier is defined as the weight, in grams, of 9000 meters of the yarn.
  • the measured denier of a yarn sample, test conditions and sample identification are fed into a computer before the start of a test; the computer records the load-elongation curve of the yarn as it is broken and then calculates the properties.
  • the amount of moisture included in a test yarn is determined by drying a weighed amount of wet yarn at 160° C. for 1 hour and then dividing the weight of the water removed by the weight of the dry yarn and multiplying by 100.
  • Residual acid or base in a yarn sample was determined by boiling a weighed, wet, yarn sample (about 20 grams) for one hour in about 200 ml deionized water and about 15 ml 0.1 N sodium hydroxide, and then titrating the solution to neutrality (pH 7.0) with standardized aqueous HCl.
  • the dry weight basis of the yarn sample was determined after rinsing the yarn several times with water and oven drying.
  • the acidity or basicity was calculated as milliequivalents of acid or base per kilogram of dry yarn.
  • the amount of sodium hydroxide added to the solution must be such that the pH of the system remains at pH 11.0 to 11.5 throughout the boiling step of the test.
  • the moisture regain of a yarn is the amount of moisture absorbed in a period of 24 hours at 70° F. and 5% relative humidity, expressed as a percentage of the dry weight of the fiber. Dry weight of the fiber is determined after heating the fiber at 105-110° C. for at least two hours and cooling it in a dessicator.
  • Apparent Crystallite Size and Crystallinity Index for poly-p-phenylene terephthalamide fibers are derived from X-ray diffractograms of the fiber materials.
  • Apparent Crystallite size is calculated from measurements of the half-height peak width of the diffraction peak at about 23° (2 ⁇ ), corrected only for instrumental broadening. All other broadening effects are assumed to be a result of crystallite size.
  • the diffraction pattern of poly-p-phenylene terephthalamide is characterized by the X-ray peaks occurring at about 20° and 23° (2 ⁇ ). As crystallinity increases, the relative overlap of these peaks decreases as the intensity of the crystalline peaks increases.
  • the Crystallinity Index of poly-p-phenylene terephthalamide is defined as the ratio of the difference between the intensity values of the peak at about 23° and the minimum of the valley at about 22° to the peak intensity at about 23°, expressed as percent. It is an empirical value and must not be interpreted as percent crystallinity.
  • X-ray diffraction patterns of yarn samples are obtained with an X-ray diffractometer (Philips Electronic Instruments; ct. no. PW1075/00) in reflection mode. Intensity data are measured with a rate meter and recorded either on a strip-chart or by a computerized data collection-reduction system. The diffraction patterns were obtained using the instrumental settings:
  • the position of the half-maximum peak height is calculated and the 2 ⁇ value for this intensity measured on the high angle side.
  • the peak breadth is converted to Apparent Crystal Size through the use of tables relating the two parameters.
  • Poly-p-phenylene terephthalamide polymer was prepared by dissolving 1,728 parts of p-phenylenediamine (PPD) in a mixture of 27,166 parts of N-methylpyrrolidone (NMP) and 2,478 parts of calcium chloride cooling to about 15° C. in a polymer kettle blanketed with nitrogen and then adding 3,243 parts of molten terephthaloyl chloride (TCl) with rapid stirring. The solution gelled in 3 to 4 minutes. The stirring was continued for 1.5 hours with cooling to keep the temperature below 25° C. The reaction mass formed a crumb-like product. The crumb-like product was ground into small particles which were then slurried with: a 23% NaOH solution; a wash liquor made up of 3 parts water and one part NMP; and, finally, water.
  • PPD p-phenylenediamine
  • NMP N-methylpyrrolidone
  • TCl molten terephthaloyl chloride
  • the slurry was then rinsed a final time with water and the washed polymer product was dewatered and dried at 100° C. in dry air.
  • the dry polymer product had an inherent viscosity (IV) of 6.3, and contained less than 0.6% NMP, less than 440 PPM Ca++, less than 550 PPM Cl-, and less than 1% water.
  • This Example describes the preparation of a series of yarns from poly-p-phenylene terephthalamide like that above-prepare which yarns differ from each other primarily in denier and moisture content.
  • An anisotropic spinning solution was prepared by dissolving the polymer in 100.1% sulfuric acid so as to produce a 19.3 wt. percent solution.
  • the spinning solution was extruded through a spinneret at about 74° C. into a 4 mm air gap followed by a coagulating bath of 10% aqueous sulfuric acid maintained at a temperature of 3° C. in which overflowing bath liquid passed downwardly through an orifice along with the filaments.
  • the spinneret had 134 to 1000 spinning holes (depending on the denier) of 0.064 millimeter diameter.
  • the filaments were in contact with the coagulating bath liquid for about 0.025 seconds.
  • the filaments were separated from the coagulating liquid, forwarded at various speeds (300-475 ypm) depending on the yarn denier desired and washed in two stages.
  • water having a temperature of 15° C. was sprayed on the yarns to remove most of the acid.
  • an aqueous solution of sodium hydroxide was sprayed on the yarns followed by a spray of water.
  • the temperature of the liquid sprays was 15° C. Residual acid or base in the yarns was determined as milliequivalents per kg of yarn.
  • the exterior of the yarns was stripped of excess water and yarns were either wound up without drying (yarn moisture of about 85%) or they were partially dried on a steam-heated roll to as low as 35 weight percent yarn moisture based on dried fiber material.
  • the polymer in the yarns so prepared had an inherent viscosity of 5.4 to 5.6. Properties of the series of yarns so produced are given in Table 1.
  • the yarns of this Example, A-G differed from each other in denier, yarn moisture, and acidity or basicity.
  • Example 1 Each of the wet yarns of Example 1 was tensioned and heat-treated in a 40 ft oven for a given time, temperature and tension. Yarn speeds were in the range of 75-200 ypm and were selected to give the desired residence times.
  • the oven was electrically heated and heated the yarns primarily by radiant heat and, only partially, by convective heat. The oven was continuously purged with nitrogen preheated to oven temperature, which, combined with steam from the drying yarn, created a nitrogen/steam atmosphere.
  • the yarn leaving the oven was advanced by a set of water-cooled rolls during which the yarn temperature was reduced to about 25° C.
  • the oven treating conditions for Examples 2-11 are given in Table 2, while the properties of the heat treated yarns are given in Table 3.
  • poly-p-phenylene terephthalamide yarns of this invention with moduli greater than about 1100 gpd, inherent viscosities greater than about 6.5, tenacities greater than 18 gpd, and crystallinity indices at least 70%, were prepared using the following oven heating conditions: oven temperature greater than 500° C. (preferably 550-660C.), heating times 4-11 sec., and tension 1.5-3.0 gpd. Note that the polymers of Examples 2 and 8 are insoluble.
  • a 380 denier, poly-p-phenylene terephthalamide yarn with 85% yarn moisture was heat-treated in an oven at 640° C. for 5.75 seconds by the same general procedure of Examples 2-11, except that the tension, during heating, was only 0.75 gpd.
  • the yarn so produced exhibited a tenacity of 15.8 gpd and a modulus of 1045 gpd.
  • the modulus of the yarn of this Example 12 would have been expected to be greater than 1250 gpd and the tenacity greater than 18 gpd for the time and , temperature utilized (see Example 10 in Tables 2 & 3 for comparison).
  • Feed yarns (Example 1, Items C, D & E) were heat-treated in an oven by the same general manner as in Examples 2-11, except that the temperatures were 450-500° C. Specific heating conditions for each Example, 13 through 16, are listed in Table 4. Heat-treated yarn properties are given in Table 5. None of the yarns of these examples exhibit the combination of modulus/inherent viscosity/tenacity/crystallinity index which represent the yarns of this invention; that is, both the moduli and inherent viscosities fall below the desired range.
  • Example 1 yarn from Example 1, Item E for all Examples except 18 and Item G for Example 18, above, was immersed in water. An end from the immersed yarn was passed through a tension gate and onto a feed roll. The resulting yarn moisture was about 100%. From the feed roll, the yarn was passed through a forwarding jet of the type shown in FIG. 1 with a barrel extender which made the overall length of the jet eight inches. In the jet, the yarn was dried and heat-treated with superheated steam or heated air, depending on the specific Example. From the jet, the yarn was passed over a draw roll so as to maintain tension on the yarn (between 2 and 4 gpd depending on the Example) in the heat-treating zone, and thence to a wind-up roll. Water was applied to the yarn just after the jet to reduce static bloom. Table 6 contains the specific feed yarn and jet conditions used for each Example, while Table 7 provides the properties of the heat-treated yarns so produced.
  • the yarns of Examples 17-22 exhibit a combination of high modulus (greater than 1100 gpd), high tenacity (greater than 18 gpd) and high crystallinity (crystallinity index, at least 76%), and Apparent Crystal Size, at least 74 ⁇ ).
  • Examples 25-33 and Comparison Examples C1-C7 describe the preparation of a series of poly-p-phenylene terephthalamide yarns using rinsing and washing processes which result in varying levels of acidity and basicity.
  • a series of nominally 400 denier (267 filaments per yarn) poly-p-phenylene terephthalamide yarns was prepared as described in Example 1 except that the second stage of washing for yarns in this series was varied from water sprays to sprays of caustic solution with increasing concentration of sodium hydroxide ranging from 0.1 to 1.8%, followed by sprays of water or caustic solution with concentrations ranging from 0.01 to 0.5%.
  • Residual acid or base in the yarns ranged from as high as 136 meq of acid per kg of yarn, through essentially neutral yarns, to as high as 106 meq of base per kg of yarn.
  • the exterior of the yarns was stripped of excess water and the yarns were wound up without drying (yarn moisture of about 85%).
  • the yarns prepared as above were tensioned and heat-treated in an oven (17 in long) at 600° C. for 5.7 sec at a tension of 2.0-2.5 gpd.
  • the properties of the yarn before and after heat treatment are given in Table 8.

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  • Artificial Filaments (AREA)
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US07/041,589 1986-05-30 1987-04-27 Process for manufacturing a high modulus poly-p-phenylene terephthalamide fiber Expired - Lifetime US4883634A (en)

Priority Applications (18)

Application Number Priority Date Filing Date Title
US07/041,589 US4883634A (en) 1986-05-30 1987-04-27 Process for manufacturing a high modulus poly-p-phenylene terephthalamide fiber
IN413/CAL/87A IN171087B (de) 1986-05-30 1987-05-25
CA000537985A CA1290117C (en) 1986-05-30 1987-05-26 High modulus poly-p-phenylene terephthalamide fiber
BR8702726A BR8702726A (pt) 1986-05-30 1987-05-27 Processo para fabricacao de uma fibra de poli-p-fenileno tereftalamida e fibra obtida pelo processo
AU73483/87A AU607420B2 (en) 1986-05-30 1987-05-28 High modulus poly-p-phenylene terephthalamide fiber
AT87304765T ATE66971T1 (de) 1986-05-30 1987-05-29 Poly-p-phenylenterephthalamidfaser mit hohem modulus.
FI872403A FI872403A (fi) 1986-05-30 1987-05-29 Hoegmodulaer poly-p -fenylentereftalamidfiber.
IL82709A IL82709A (en) 1986-05-30 1987-05-29 High modulus poly-p-phenylene terephthalamide fibers and their manufacture
DK275587A DK275587A (da) 1986-05-30 1987-05-29 Poly-p-phenylen-terephthalamidfibre og fremgangsmaade til deres fremstilling
DE8787304765T DE3772628D1 (en) 1986-05-30 1987-05-29 Poly-p-phenylenterephthalamidfaser mit hohem modulus.
KR1019870005386A KR940002380B1 (ko) 1986-05-30 1987-05-29 고탄성율의 폴리-p-페닐렌 테레프탈아미드 섬유 및 이의 제조방법
ES87304765T ES2025162B3 (es) 1986-05-30 1987-05-29 Fibra de poli-p-fenilentereftalamida de modulo elevado.
NO872270A NO169138C (no) 1986-05-30 1987-05-29 Poly-p-fenylenterefthalamidfiber og fremgangsmaate for fremstilling av denne
EP87304765A EP0247889B1 (de) 1986-05-30 1987-05-29 Poly-p-phenylenterephthalamidfaser mit hohem Modulus
MX006705A MX166780B (es) 1986-05-30 1987-05-29 Procedimiento de fabricacion de una fibra de poli-p-fenilen tereftalamida
PT84981A PT84981B (pt) 1986-05-30 1987-05-29 Processo para a fabricacao de fibras de poli-p-fenileno-tereftalamina com um grande valor do modulo
JP62133544A JPH0778289B2 (ja) 1986-05-30 1987-05-30 高モジユラス性ポリ−ｐ−フエニレンテレフタルアミド繊維
GR91401216T GR3002645T3 (en) 1986-05-30 1991-09-05 High modulus poly-p-phenylene terephthalamide fiber

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US07/041,589 US4883634A (en) 1986-05-30 1987-04-27 Process for manufacturing a high modulus poly-p-phenylene terephthalamide fiber

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KR (1) KR940002380B1 (de)
AT (1) ATE66971T1 (de)
AU (1) AU607420B2 (de)
BR (1) BR8702726A (de)
CA (1) CA1290117C (de)
DE (1) DE3772628D1 (de)
DK (1) DK275587A (de)
ES (1) ES2025162B3 (de)
FI (1) FI872403A (de)
GR (1) GR3002645T3 (de)
IL (1) IL82709A (de)
IN (1) IN171087B (de)
MX (1) MX166780B (de)
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5009830A (en) * 1989-03-20 1991-04-23 E. I. Du Pont De Nemours And Company On-line fiber heat treatment
US5175239A (en) * 1990-12-27 1992-12-29 E. I. Du Pont De Nemours And Company Process for making para-aramid fibers having high tenacity and modulus by microwave annealing
US20090092830A1 (en) * 2007-10-09 2009-04-09 Bhatnagar Chitrangad High linear density, high modulus, high tenacity yarns and methods for making the yarns
US20100001433A1 (en) * 2006-11-21 2010-01-07 Teijin Aramid B.V. Method for obtaining high-tenacity aramid yarn

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU607104B2 (en) * 1988-03-02 1991-02-21 E.I. Du Pont De Nemours And Company Method of preparing poly(p-phenyleneterephthalamide) yarns of improved fatigue resistance
US4821427A (en) * 1988-04-18 1989-04-18 E. I. Du Pont De Nemours And Company Method and apparatus for reducing the moisture content of wet yarns
CA1319502C (en) * 1988-07-06 1993-06-29 Terry S. Chern Fiber creel humidification
JP3676111B2 (ja) * 1998-06-03 2005-07-27 帝人テクノプロダクツ株式会社 芳香族ポリアミド繊維及びそれを用いた紙
PL2218807T3 (pl) * 2009-02-17 2012-05-31 Teijin Aramid Bv Obróbka cieplna dla zwiększenia wytrzymałości na ściskanie przędzy PPTA

Citations (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3063966A (en) * 1958-02-05 1962-11-13 Du Pont Process of making wholly aromatic polyamides
US3673143A (en) * 1970-06-24 1972-06-27 Du Pont Optically anisotropic spinning dopes of polycarbonamides
US3817941A (en) * 1967-12-27 1974-06-18 Du Pont Wholly aromatic carbocyclic poly-carbonamide fiber having initial modulus in excess of 170 gpd and orientation angle of up to 40 grad
US3862897A (en) * 1969-09-05 1975-01-28 Rhone Poulenc Sa Method of forming high elongation polymide-imide films
US3869429A (en) * 1971-08-17 1975-03-04 Du Pont High strength polyamide fibers and films
US3869430A (en) * 1971-08-17 1975-03-04 Du Pont High modulus, high tenacity poly(p-phenylene terephthalamide) fiber
GB2044669A (en) * 1979-03-13 1980-10-22 Asahi Chemical Ind High young's modulus poly - p - phenylene - terephthalamide fibres
GB2044668A (en) * 1979-03-13 1980-10-22 Asahi Chemical Ind Poly - p - phenylene - terephthalamide fibres excellent in fatigue resistance
US4346215A (en) * 1980-03-17 1982-08-24 E. I. Du Pont De Nemours And Company Film of aromatic polyamide and process therefor
JPS59192713A (ja) * 1983-04-18 1984-11-01 Teijin Ltd 芳香族ポリアミド繊維の延伸方法
US4507467A (en) * 1980-08-07 1985-03-26 Teijin Limited Wholly aromatic halogenated polyamide fiber and film
US4539393A (en) * 1982-04-13 1985-09-03 Teijin Limited Dimensionally stable poly-m-phenylene isophthalamide film
US4560743A (en) * 1983-09-02 1985-12-24 Asahi Kasei Kogyo Kabushiki Kaisha Poly(P-phenyleneterephthalamide) fibers

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2211241B2 (de) * 1972-03-08 1979-02-22 Vsesojuznyj Nautschno-Issledovatelskij Institut Iskusstvennogo Volokna, Mytischtschi, Moskovskoj Oblasti (Sowjetunion) Verfahren zur Herstellung von hxxochfesten wärmebeständigen Fasern aus Polyamiden
US4162346A (en) * 1976-09-23 1979-07-24 Celanese Corporation High performance wholly aromatic polyamide fibers
JPS5511763A (en) * 1978-07-12 1980-01-26 Meisan Kk Control method and device of strip cutter
JPS5511764A (en) * 1978-07-12 1980-01-26 Yamamoto Kyoshi Monkey spanner
JPS591710A (ja) * 1982-06-18 1984-01-07 Asahi Chem Ind Co Ltd 新規な構造のポリ（ｐ−フエニレンテレフタルアミド）繊維およびその製法
JPS608817A (ja) * 1983-06-29 1985-01-17 Matsushita Electric Ind Co Ltd 試料載物板

Patent Citations (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3063966A (en) * 1958-02-05 1962-11-13 Du Pont Process of making wholly aromatic polyamides
US3817941A (en) * 1967-12-27 1974-06-18 Du Pont Wholly aromatic carbocyclic poly-carbonamide fiber having initial modulus in excess of 170 gpd and orientation angle of up to 40 grad
US3862897A (en) * 1969-09-05 1975-01-28 Rhone Poulenc Sa Method of forming high elongation polymide-imide films
US3673143A (en) * 1970-06-24 1972-06-27 Du Pont Optically anisotropic spinning dopes of polycarbonamides
US3869429A (en) * 1971-08-17 1975-03-04 Du Pont High strength polyamide fibers and films
US3869430A (en) * 1971-08-17 1975-03-04 Du Pont High modulus, high tenacity poly(p-phenylene terephthalamide) fiber
GB2044669A (en) * 1979-03-13 1980-10-22 Asahi Chemical Ind High young's modulus poly - p - phenylene - terephthalamide fibres
GB2044668A (en) * 1979-03-13 1980-10-22 Asahi Chemical Ind Poly - p - phenylene - terephthalamide fibres excellent in fatigue resistance
US4374977A (en) * 1979-03-13 1983-02-22 Asahi Kasei Kogyo Kabushiki Kaisha Poly-p-phenylene-terephthalamide fibers excellent in fatigue resistance and process for preparation thereof
US4374978A (en) * 1979-03-13 1983-02-22 Asahi Kasei Kogyo Kabushiki Kaisha High Young's modulus poly-p-phenylene terephthalamide fiber
US4346215A (en) * 1980-03-17 1982-08-24 E. I. Du Pont De Nemours And Company Film of aromatic polyamide and process therefor
US4507467A (en) * 1980-08-07 1985-03-26 Teijin Limited Wholly aromatic halogenated polyamide fiber and film
US4539393A (en) * 1982-04-13 1985-09-03 Teijin Limited Dimensionally stable poly-m-phenylene isophthalamide film
JPS59192713A (ja) * 1983-04-18 1984-11-01 Teijin Ltd 芳香族ポリアミド繊維の延伸方法
US4560743A (en) * 1983-09-02 1985-12-24 Asahi Kasei Kogyo Kabushiki Kaisha Poly(P-phenyleneterephthalamide) fibers

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Journal of East China Institute of Textile Science and Technology, vol. 10, No. 2, (1984), pp. 30 34. *
Journal of East China Institute of Textile Science and Technology, vol. 10, No. 2, (1984), pp. 30-34.

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5009830A (en) * 1989-03-20 1991-04-23 E. I. Du Pont De Nemours And Company On-line fiber heat treatment
US5175239A (en) * 1990-12-27 1992-12-29 E. I. Du Pont De Nemours And Company Process for making para-aramid fibers having high tenacity and modulus by microwave annealing
US20100001433A1 (en) * 2006-11-21 2010-01-07 Teijin Aramid B.V. Method for obtaining high-tenacity aramid yarn
US8501071B2 (en) * 2006-11-21 2013-08-06 Teijin Aramid B.V. Method for obtaining high-tenacity aramid yarn
US8826636B2 (en) 2006-11-21 2014-09-09 Teijin Aramid B.V. Method for obtaining high-tenacity aramid yarn
US20090092830A1 (en) * 2007-10-09 2009-04-09 Bhatnagar Chitrangad High linear density, high modulus, high tenacity yarns and methods for making the yarns

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PT84981A (en) 1987-06-01
EP0247889A2 (de) 1987-12-02
JPS6321918A (ja) 1988-01-29
ES2025162B3 (es) 1992-03-16
IL82709A0 (en) 1987-11-30
NO872270D0 (no) 1987-05-29
FI872403A (fi) 1987-12-01
IN171087B (de) 1992-07-18
DK275587A (da) 1987-12-01
DE3772628D1 (en) 1991-10-10
JPH0778289B2 (ja) 1995-08-23
NO872270L (no) 1987-12-01
IL82709A (en) 1990-12-23
NO169138B (no) 1992-02-03
AU607420B2 (en) 1991-03-07
AU7348387A (en) 1987-12-03
CA1290117C (en) 1991-10-08
FI872403A0 (fi) 1987-05-29
KR940002380B1 (ko) 1994-03-24
GR3002645T3 (en) 1993-01-25
EP0247889B1 (de) 1991-09-04
NO169138C (no) 1992-05-13
KR870011285A (ko) 1987-12-22
DK275587D0 (da) 1987-05-29
PT84981B (pt) 1990-02-08
MX166780B (es) 1993-02-04
ATE66971T1 (de) 1991-09-15
BR8702726A (pt) 1988-03-01
EP0247889A3 (en) 1988-09-28

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